1. Field of the Invention
This invention relates to a system for monitoring the operating efficiency of pipelines and pipeline pump stations.
2. Discussion of Related Art
In order to transport materials such as oil, coal, water, and natural gas over large distances, pipeline distribution systems are used which comprise a plurality of pipeline pumping stations spaced along a long pipeline through which the fluid is passed. Each pipeline pumping station normally consists of a number of pumping units wich may be of different sizes or capacity. These pumping units are sometimes individually connected for use and are controlled to maintain the flow rate through the pumping station as close as possible to a desired level. Optimally, each pumping station adds a predetermined amount of hydraulic power to the pipeline in order to maintain the desired flow rate.
In the past, the operation of starting and stopping the pumping units at a pumping station has been done manually by an operator or by remote control from a master station. This method of control has been improved upon by the advent of automatic controllers, such as that shown in U.S. Pat. No. 3,068,796 to Pfluger et al. The Pfluger et al system automatically starts and stops pumping units in a pumping station in order to maintain the power level of the pump station at the power level set either by remote or local commands.
However, even with the use of automatic controllers, difficulties exist when trying to transport materials over a large distance at an economical rate. For example, in the controller of Pfluger et al, emphasis is placed on single elements and control is effected assuming that average parameters are the same as instantaneous values, and that loading is shared equally. However, in actual fact, instantaneous parameters may fluctuate greatly thus severely reducing the overall efficiency of a pumping station. The material being transported is normally distributed at a high pressure and, therefore, transmits forces among the pumping units of the station. Consequently, each pumping unit may be operating at conditions which are different from the average obtained by measuring the total throughput of the station or from time averaged parameters for the individual units. This problem is further compounded by the possiblity of resonant interaction among pumping station components. Large instantaneous excursions can develop and persist until damage to elements of the station occurs. Even if such damage does not occur, such fluctuations and oscillations can result in an average operating efficiency which is substantially below that which is optimal, even though the pumping station is operating at a desired power level. Also, the total load of the pumping station may not be equally shared among the pumping units. This results in the different pumping units operating at different efficiency levels thus causing a still greater decrease in operating efficiency.
Various systems are known for monitoring the operation of mechanical components. For example, U.S. Pat. No. 4,286,324 to Ingram shows a system for controlling the power transmitted through a rotating shaft. U.S. Pat. No. 3,988,093 to Bertolasi shows an energy monitoring system which is used to monitor the gas or electrical energy consumed by a factory or the like. U.S. Pat. No. 3,285,057 shows an apparatus for measuring the torsional reaction of a fluid on a rotating shaft.
Also, my own U.S. Pat. No. 4,334,425, issued June 15, 1982, shows a system for analyzing the efficiency of power plants, and especially marine power plants.
However, none of the known systems is adapted specifically for use in a material pipeline distribution system for identifying the unique problems encountered in such a system. The present invention is an improvement upon my aforementioned U.S. Pat. No. 4,334,425 adapted specifically for use in a pipeline distribution system. However, many of the components of my aforementioned patent can be used directly in the present invention, and the disclosure of my aforementioned patent is incorporated by reference herein for the purpose of further explanation of these components.